The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In order to design and fabricate low profile (slim) LLC resonant converters, it is essential to replace conventional wire-wound magnetic transformers with low profile planar ones. In planar transformers, to decrease high-frequency AC resistance and to get high power efficiency, the primary and secondary PCBs are stacked together using the interleave structure method, which leads to a high amount of...
In this paper a unified Impedance-based Stability Criterion (UIBSC) has been proposed for paralleled grid-tied inverters. Compared to the traditional Impedance-based Stability Criterion (IBSC) which needs to evaluate all minor loop gains (MLGs) of each individual inverter, the UIBSC only checks the derived global minor loop gain (GMLG) once to determine system stability. As a result, the computation...
Detecting the load currents is a basic control method of paralleled active power filter (PAPF). The stability and compensation effect of the system would be influenced by the interactions of the load, weak grid and the paralleled active power filter (PAPF), when the load can't be equivalent to an ideal harmonic current source. The impedance models are established to analyze the stability of the system,...
In this paper, a radial-chordal decomposition (RCD) technique is proposed to decouple the power angle and voltage control of a smart load based on the use of electric springs (ES). The paper gives a highlight of the decoupling feature and the merit of achieving multiple functionalities within a single ES. This RCD control method has been tested on a 2 kW small-scale power system. Experimental results...
Photovoltaic power plants (PV) are equipped with anti-islanding algorithms, embedded in the converters controller, to avoid the island operation. However, the current trends in the development of the future electrical networks evidence that it is technically feasible and economically advantageous to keep feeding islanded systems under these situations, without cutting the power supply to the loads...
Distributed generation (DG) has gained popularity in recent years due to the increasing requirement for renewable power sources. A problem that exists with DG systems is the islanding of DG units that creates safety issues for personnel as well as the potential for damage to utility infrastructure. Therefore, islanding detection methods are utilized to mitigate the risk of islanded operation of DG...
In this paper, an improvement in power sharing for Autonomous Microgrid is well established. All previous studies were based on voltage and frequency droop control to share power between distributed generators. This paper develops a new robust voltage and angle droop control to share power, where its advantage over the common frequency droop is in less frequency variation. The synchronization of Power...
The grid-feeding voltage controlled inverter (GF-VCI) based on droop control is vulnerable to the harmonic voltages of the utility grid. Because of the equivalent impedance of system is small, the slight distorted grid voltage will result in the harmonic component increasing of GF-VCI output currents. Therefore, the reason of generation of distorted grid-feeding current of GF-VCI under the distorted...
This research proposes a bridgeless rectification circuit for impedance matching and voltage boosting of a Wi-Fi energy harvesting system. The impedance matching is achieved by an LCL T-network in parallel with an inductive branch, and such an arrangement can boost the voltage by combined effect of T-network and bipolarity charging of the output capacitor. The return loss equation and an estimated...
The interaction between STATCOM and voltage-source inverter (VSI) may cause instability in an islanded micro-grid. Impedance models of storage battery power convert system (PCS) and cascaded multilevel static synchronous compensator (STATCOM) are established based on which the interaction mechanism between PCS and STATCOM is studied. Using Nyquist stability criterion and admittance ratio analysis,...
In order to address the power quality enhancement in a given microgrid, independent control of reactive, unbalanced and distorted load current components, in a multi-inverter-based approach may be required. Therefore, this paper proposes a coordinated control strategy using the Conservative Power Theory (CPT) and assuming the contribution of all grid connected interfaces, especially those related...
In highly microgrid (MG) integrated distribution systems, problems such as a sudden cut out of the MGs due to grid faults may lead to adverse effects to the grid. As a consequence, ancillary services provided by MGs are preferred since it can make the MG a contributor to ride through the faults. In this paper, a voltage support strategy based on negative sequence droop control, which regulate the...
The high penetration level of power electronics interfaced Distributed Generation (DG) systems creates great ancillary services potential through the DG interfacing converters (IFCs) such as the grid unbalanced voltage compensation. However, the unbalanced voltage compensation may cause adverse effects on the IFCs' operation such as output active power oscillation and DC link voltage variations. Moreover,...
This paper introduces a new isolated resonant dc-dc converter topology based on the recently proposed impedance control network (ICN) converter architecture. This new converter maintains very high efficiency by achieving zero voltage switching (ZVS) and near zero current switching (ZCS) across a very wide operating range. Additional performance enhancement is achieved through a new design methodology...
Stability analysis of cascaded DC-DC converters systems is one of fundamental issues crucial to real-world power supplies applications. Existing techniques for stability analysis of cascaded converters systems are mainly based on Thevenin or Norton equivalents of two-port networks of sub-converters in which impedance-based stability criteria can be applied. In this work, further transformations of...
This paper addresses the limitation of current technologies in the interconnection between medium-voltage (MV) DC and high-voltage (HV) DC grids. One transformerless approach is proposed to achieve bidirectional high power transfer and high step up/down ratio, which can be configured to interface with different grids connection. The proposed technology integrates modular multilevel converter (MMC)...
This paper presents a finite control set Model Predictive Control (FS-MPC) approach for a grid-connected converter, particularly suitable for non-stiff grids where under low Short Circuit Ratio (SCR) the performance of the controller may get affected by variations in supply impedance value. In order to avoid this problem, a novel supply inductance estimator that is based on the grid currents variations...
In recent years, with the promotion and application of photovoltaic (PV) technology, research on grid-connected inverters incorporating with weak grid has become a hot field. In general, the large grid impedance will reduce the gain and bandwidth of the control system and slow down the dynamic response, or even lead to resonance and instability of the whole control system. Especially, when the grid...
One of the problems encountered when a wind farm is radially connected to a series compensated transmission line is subsynchronous resonance (SSR). The aim of this paper is to investigate the risk of SSR condition in Doubly-Fed Induction Generator (DFIG) based wind farms that are radially connected to series compensated transmission lines. The IEEE First Benchmark Model (IEEE FBM) is adopted and the...
Short circuit fault emulation is an important capability for power converter based grid emulator. This paper proposes to use a shunt connected voltage source converter to emulate short circuit faults, including single-line-to-ground, double-line-to-ground, line-to-line, and three-phase faults. The operating principle and hardware requirements are discussed first, and control strategies for each type...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.